Automatic drain valve



5. S. AIKMAN AUTOMATIC DRAIN VALVE Jul 26, 1938.

Filed Aug. 14, 1956 INVENTOR EURTUN EAIKMAN ATTQRNEY Patented July 26, 1938 UNITED STATES PATENT OFFICE AUTOMATIC DRAIN VALVE Application August 14,

11 Claims.

This invention relates to an automatic drain valve for use on a reservoir or receiver for fluid under pressure and which operates to release moisture from this receiver or reservoir.

In the operation of fluid pressure systems, such as fluid pressure brake systems, air from the atmosphere is compressed and is stored in a reservoir or receiver from which fluid is withdrawn during operation of the brake equipment. As a result of the supply of fluid under pressure to and the release of fluid under pressure from the reservoir, water is deposited in the reservoir and unless it is periodically drained away it accumulates in the reservoir and reduces the volume of the reservoir, while it may freeze and cause injury to the equipment.

It is an object of this invention to provide valve means adapted to be employed to release liquid which accumulates in the reservoir ofa fluid pressure system.

A further object of the invention is to provide a valve device automatically operable in response to variations in the pressure of the fluid in a reservoir or receiver for controlling a communication through which liquid may be released from the reservoir or receiver.

Another object of the invention is to provide a valve device of the type described which releases fluid from the receiver in limited volumes so that the supply of fluid in the receiver will not be unduly depleted by operation of the valve device.

A further object of the invention is to provide a valve device of the type described which is of rugged construction, and in which the elements are of such design as not to be damaged if water present in the device freezes.

A further object of the invention is to provide an improved automatic drain valve device. I

:Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawing, the single figure of which is a. sectional view showing a drain valve device embodying my invention.

Referring to the drawing, there is illustrated therein a portion of a receiver or reservoir I for a fluid pressure system which is supplied with fluid under pressure by a suitable compressor, 50 not shown, and from which fluid is withdrawn through a suitable pipe, not shown.

The drain valve device provided by myinvention is mounted in a threaded opening in the lowermost portion of the reservoir or receiver I, and, as shown, comprises a hollow body 2 having tubu- 1936, Serial No. 98,009

lar threaded portion 4 adapted to be received by the threaded opening in the reservoir I.

The body 2 has an annular chamber 6 formed.

therein and the upper portion of this chamber is of larger cross-sectional area than the lower portions thereof. The body 2 has a tubular sleeve portion, indicated as 8, formed integral therewith and extending downwardly from the upper wall of the chamber 6 substantially to the face of the threaded plug I8 which closes the lower portion of the chamber 6. The plug ID has a release passage I2 extending therethrough.

The tubular sleeve portion 8 has a bore therein in which is mounted a movable abutment or element in the form of a piston I4 having a central boss thereon through which extends a passage in which is mounted a valve member I8 having a fluted stem I6. The valve member I8 is adapted to engage a seat formed on the piston I4 surrounding the upper end of the passage through the piston.

A spring 28 is provided and extends between the piston I4 and a spring seat 22 secured on the stem I6 of the valve I8 so as to yieldingly press the valve I8 into engagement with its seat. The spring 28 is under slight initial compression so that it lightly presses the valve I8 against the piston I4 and so that a small force is required to unseat the valve I8.

The lower end of the stem I6 of the valve I8 has a substantially conical face thereon indicated at 24, which is adapted to seat upon a seat formed on the plug I0 surrounding the release passage I2.

In initially charging the equipment, fluid under pressure is supplied to the reservoir I and it exerts force on the upper face of the piston I4 to press the piston downwardly. On downward movement of the piston I4, the face 24 on the end of the stem I6 is pressed into engagement with the seat surrounding the release passage I2, so that on further downward movement of the piston I4, the spring 28 is compressed, while the piston I4 is moved relative to the valve I8 so that the seat on the piston I4 is moved away from the valve I 8.

When the piston I4 is moved relative to the valve I8, fluid under pressure from the reservoir I flows through the passage through the piston I4 to the chamber 6 to increase the pressure of the fluid in this chamber. On an increase in the pressure of the fluid in the chamber 6 to a predetermined value below that in the reservoir I, the force exerted by the fluid under pressure in the chamber 6, together with the force exerted by the spring 20 on the piston l4, overcomes the opposing force of the fluid under pressure in the reservoir I on the piston I4, and the piston is thereupon moved upwardly until the seat on the piston engages the valve I8 to cut off the further supply of fluid under pressure from the reservoir I to the chamber 6.

After movement of the piston I4 into engagement with the valve I8, the pressure of the fluid in the chamber 6 continues to build up by leakage of fluid thereto from the reservoir I past the piston I4 until the pressure of the fluid in the chamber 6 is substantially at the pressure of the fluid in the reservoir I.

On this increase in the pressure of the fluid in the chamber 6, the valve I8 is held in the seated position by the spring 20, while the face 24 on the end of the stem I6 of the valve I8 is held in engagement with the seat on the plug Ill surrounding the release passage I2 by the weight of the piston I4 and the valve I8 and by the fluid under pressure in the reservoir I acting on an area of the valve I8 equal to the area surrounded by the seat on the plug II! which is engaged by the face 24.

Any liquid which accumulates in the reservoir I flows by gravity to the lower portion thereof, and through the passage in the tubular portion 4 of the drain valve device to the chamber at the face of the piston I4. 7

On a subsequent reduction in the pressure of the fluid in the reservoir I as a result of the withdrawal of fluid therefrom, there is a reduction in the force exerted by this fluid on the piston I4 in opposition to the opposing force of the fluid in the chamber 6, and the piston I4 is thereupon moved upwardly by the fluid under pressure in the chamber 6.

On this movement of the piston I4, the face 24 on the end of the stem I6 is lifted away from the seat surrounding the release passage I2 so as to release fluid from the chamber 6 and thereby reduce the pressure of the fluid in this chamber.

On a reduction in pressure of the fluid in the chamber 6 to a value equal to or slightly below the pressure of the fluid in the reservoir I, the fluid under pressure in the reservoir I moves the piston I4 downwardly so as to move the valve face 24 on the end of the stem I 6 into engagement with the seat on the plug I surrounding the release passage I2 to cut off the release of fluid from the chamber 6. V

The volume of fluid released from the chamber 6 before the pressure of the fluid in this chamber is reduced to a value equal to or slightly below the pressure of the fluid in the reservoir I is relatively small because ofthe relatively small volume of the chamber 6.

On a subsequent increase in the pressure of the fluid in the reservoir I as a result of the supply of fluid thereto by operation of the compressor, the pressure of the fluid in the reservoir will exceed the pressure of the fluid in the chamber 6 on the opposite face of the piston I4 and when the pressure of. the fluid in the reservoir I has increased to a predetermined value above the pressure of the fluid in the chamber 6, the force exerted on the piston I4 by this fluid will exceed the opposing force exerted on the piston I4 by the fluid in the chamber 6 by an amount sufficient to move the piston I4 downwardly against the opposing force of the spring '20, while the valve face 24 on the end of the stem I6 is pressed more firmly into engagement with the seat surrounding the release passage I2.

On this movement of the piston I4, the seat on the piston is moved away from the valve I8 so as to permit liquid accumulated in the chamber above the piston I4 to flow through the passage through the piston I4 to the chamber 6 at the opposite face of this piston. This liquid will flow past the lower end of the tubular sleeve portion 8, and the level of the liquid in the chamber 6 will increase until the pressure of the fluid trapped in the upper portion of the chamber 6 is increased substantially to the pressure of the fluid in the reservoir I.

On an increase in the pressure of the fluid in the chamber 6 there is an increase in the force acting on the piston I4 in opposition to the force exerted thereon by the fluid under pressure in the reservoir I, and when the pressure of the fluid in the chamber 6 is increased substantially to the pressure of the fluid in the reservoir I, the piston I4 will be moved upwardly by this fluid under pressure, assisted by the spring 29, until the seat on the piston I4 engages the valve I8 to cut off the flow of fluid from the reservoir I to the chamber 6 through the passage controlled by the valve I8.

On movement of the piston I4 upwardly into engagement with the valve I8, the spring 28 is no longer effective to exert force on the piston I4 tending to move it upwardly, while the pressure of the fluid in the chamber 6 is thereafter increased by leakage of fluid from the reservoir I past the piston I4 until the pressure of the fluid in the chamber 6 is built up substantially to the pressure of the fluid in the reservoir I. The face 24 'on the end of the stem I6 is held in engagement with the seat surrounding the release passage I2 by the weight of the piston I4 and the valve I8 so as to cut off the release of fluid from ber 6, the force exerted by the fluid under pressure in the reservoir I on the piston I4 is insufflcient to hold this piston against the opposing force of the fluid under pressure in the chamber 6, and the piston I4 is thereupon moved upwardly in the bore in the tubular sleeve portion 8. On this movement of the piston I4, the valve I8 is lifted so that the valve face 24 on the stem I6 is out of engagement with the seat surrounding the release passage I2 and the liquid in the lower portion of the chamber 6 is forced out through the release passage I 2 by the fluid under pressure trapped in the upper portion of the chamber '6.

After a predetermined amount of liquid is released from the chamber 6, the pressure of the fluid remaining in this chamber is insufficient to maintain the piston I4 against the opposing force of the fluid under pressure in the reservoir I, and the piston I4 is thereupon moved downwardly by the fluid under pressure in the reservoir I until the valve face 24 on the end of the stem I6 engages the seat surrounding the passage I2 ,so as to cut off the further release of fluid from the chamber 6.

On a subsequent increase in the pressure of the fluid in the reservoir I, the piston I4 is moved downwardly against the spring 28 so as to permit ber 6 to increase the pressure of the fluid in this chamber substantially tothe pressure of the fluid in the reservoir I, and the piston I4 is thereafter again moved upwardly until the seat thereon engages the valve I8.

On the next reduction in the pressure of the fluid in the reservoir I, the drain valve device operates as described in detail above to again release liquid from the chamber 6, and this cycle of operation is repeated on subsequent fluctuations in the pressure of the fluid in the reservoir I.

It will be seen that the volume of fluid, either liquid or gaseous, released by the drain valve device on each fluctuation of the pressure of the fluid in the reservoir l is relatively small so that the fluid under pressure in the reservoir I will not be unduly depleted by operation of the drain valve device. The amount discharged by the drain valve device on each operation thereof is, however, proportioned so that the drain valve device is enabled to maintain the reservoir l substantially free from moisture.

It will be seen also that the chamber 6 in the body 2 of the drain valve device has a curved outer wall which increases in diameter away from the bottom wall of the'chamber, and that this chamber is only partially filled with liquid. As a result, if the liquid in this chamber should freeze, the ice which is formed will not adhere to the inner face of the wall of the chamber 6 so as to cause such pressure to be developed as would result in injury to portions of the valve device, or fracture the housing of the device.

It will be seen in addition, that this drain valve device operates automatically in response to variations in the pressure of the fluid in reservoir I, and that it requires no attention on the part of the operator of the fluid pressure system with which it is associated.

While one embodiment of the improved auto matic drain valve device provided by my invention has been illustrated and described in detail, it should be understood that the invention is not limited to these details of construction, and that numerous changes and modifications may be made without departing from the scope of the following claims.

Having now described my invention, what I claim as new and desireto secure by Letters Patent, is:

1. In a drain valve device for a reservoir, a body having a chamber therein, a movable element subject to the opposing pressures of the fluid in said reservoir and of the fluid in said chamber, and valve means operated by said element for controlling communication from the reservoir to said chamber and for also controlling communication from said chamber to the atmosphere.

2. In a drain valve device for a reservoir, a body having a chamber therein, a movable element subject to the opposing pressures of the fluid in said reservoir and of the fluid in said chamber, and valve means operated by said element for controlling the flow of fluid from the reservoir to said chamber, and for also controlling the release of fluid from said chamber.

3. In a drain valve device for a reservoir, a body having a chamber therein, a movable element subject to the opposing pressures of the fluid in said reservoir and of the fluid in said chamber, and a valve associated with said element, said valve being movable relative to the element by movement of the element for controlling communication between the reservoir and said chamber, and being movable with said element for controlling the release of fluid from said chamber.

4. In a drain valve device for a reservoir, a body having a chamber therein, a movable element subject to the opposing pressures of the fluid in said reservoir and of the fluid in said chamber, a valve associated with said element, said valve being movable relative to the element by movement of the element for controlling communication between the reservoir and said chamber, and being movable with said element for controlling the release of fluid from said chamber, and means yieldingly opposing relative movement between said valve and said element.

5. In a drain valve device for a reservoir, in combination, a body having a chamber therein and having a release passage surrounded by a seat communicating with said chamber, a movable element subject to the opposing pressures of the fluid in the reservoir and in said chamber, said element having a passage therethrough surrounded bya seat, and a valve member having valve faces thereon adapted to engage the seats on said body and on said element.

6. In a drain valve device for a reservoir, in combination, a body having a chamber therein and having a release passage surrounded by a seat communicating with said chamber, a movable element subject to the opposing pressures of the fluid in the reservoir and in said chamber, said element having a passage therethrough surrounded by a seat, a valve member having faces thereon adapted to engage the seats on said body and on said element, and means yieldingly urging a face on said valve member into engagement with the seat on said element.

'7. In a drain valve device for a reservoir, in combination, a body having a chamber therein and having a release passage surrounded by a seat communicating with said chamber, a movable element subject to the opposing pressures of the fluid in the reservoir and in said chamber, said element having a passage therethrough surrounded by a seat, a valve member carried by said element and having .a face thereon adapted to engage the seat on said element, said valve member having another face thereon adapted to engage the seat on the body.

8. In a drain valve device for a reservoir, in combination, a body having a chamber therein and having a release passage surrounded by a seat communicating with said chamber, a movable element subject to the opposing pressures of the fluid in the reservoir and'in said chamber, said element having a passage therethrough surrounded by a seat, a valve member carried by said element and having a face thereon adapted to engage the seat on said element, said valve member having another face thereon adapted to engage the seat on the body, and means yieldin-gly urging said valve member into engagement With the seat on said element.

9. In a drain valve device for a reservoir, in combination, a body having a chamber therein having a passage adapted to communicate with said reservoir, said passage opening into said chamber at the lower portion thereof, means subject to the opposing pressures of the fluid in said chamber and of the fluid in the reservoir and operative on an increase in the pressure of the fluid in the reservoir to open a communication through which water accumulated in the reservoir may drain from the reservoir through said passage to said chamber and through which fluid under pressure may be supplied to said. chamber,

chamber may drain therefrom.

10. In a drain valve device for a reservoir; in combination, a body having a substantially ver tically extending bore therein, said body having a chamber associated therewith adapted to contain fluid under pressure and also having a com munication between the lower portion of said bore and the lowermost portion of said chamber, a piston reciprocable in said bore, said piston being subject on one side to the pressure of the fluid in the reservoir and subject on the other side to the pressure of the fluid in said chamber, valve means operable on an increase in the pressure of the fluid in the reservoir to a value exceeding the pressure of the fluid in said chamber .to open a communication through which liquid accumulated in said reservoir may drain to said chamber through said communication and through which fluid under pressure may be supplied to said chamber, and valve means operated by said piston on a reduction in the pressure of the fluid in the reservoir to a value below the pressure of the fluid in the chamber to open 2.

communication through which liquid may drain from said chamber. 7 V p 11. In a drain valve device for a reservoir, in combination, a body having a substantially vertically extending bore therein, said body having a chamber therein adapted to contain fluid under pressure and also having a communication between the lower portion of said bore and the lower portion of said chamber, a piston reciprocable in said bore, said piston being subject on one side to the pressure of the fluid in the reservoir and subject on the other side to the pressure of the fluid in said chamber, valve means operated by said piston on an increase in the pressure of the fluid in the reservoir to a value exceeding the pressure of the fluid in said chamber to open a communication through which liquid accumulated in said reservoir may drain to said chamber through said communication and through which fluid under pressure may be supplied to said chamber, and valve means operated by said piston on a reduction in the pressure of the fluid in the reservoir to a value below the pressure of the fluid in the chamber to open a communication through which liquid may drain from said chamber.

BURTON S. AIKMAN. 

